This invention relates to means for introducing additional air into the air-fuel stream of internal combustion engines and, more particularly, to the means set forth above by which more complete combustion of the fuel is obtained to reduce the amount of carbon monoxide CO and hydrocarbon HC to be discharged through an exhaust pipe in an automobile.
In an internal combustion engine, it is the normal procedure that the intake manifold, its connection to the internal combustion chambers, and the connection of the carburetor to the manifold are all made to be perfect seals so that the air is introduced into the intake manifold only from the air intake port of the carburetor. However, such an air intake system does not allow sufficient air to be mixed with the fuel to attain complete combustion, consequently there is an excess of fuel which causes the production of free carbon which is deposited in the upper parts of the combustion chamber and the exhaust pipe and is emitted into the air.
Along with the free carbon there is a large amount of carbon monoxide CO which is the result of burning a carbon compound with insufficient air. At the same time some of the fuel in an unburned condition is emitted from the exhaust of the engine as hydrocarbon gas HC.
In order to eliminate the production of free carbon, carbon monoxide and hydrocarbon, it is a logical fact that more air is necessary to burn all of the fuel used in the internal combustion engine, but there have been physical limitations in the system of fuel introduction to the engine and mixing of the fuel with the air. Further, the air-fuel mixture must be a very intimate mixture.
To obtain a more complete combustion of the fuel, it may be designed to introduce additional air into the air-fuel stream delivered from the carburetor. For this end, if a single air hole having a diameter large enough to introduce sufficient air therethrough is made through the intake manifold, the air entering into the intake manifold will become a jet flow and thereby create a cross turbulence in the air-fuel stream from the carburetor. The term "cross turbulence" used herein means a turbulence in the radial direction of the intake passage. Such a turbulence restricts the normal axial flow of the air-fuel stream and causes instability in the operation of the internal combustion engine. Also, a volume of air from the large air hole will cause a reduction of the intake manifold vacuum to below the operating limits thereof. For the reasons set forth above, the engine will not run with such a hole made through the intake manifold.
Accordingly, an object of the present invention is to provide means for introducing additional air into the air-fuel stream of internal combustion engines for more complete combustion of the fuel, thereby not only reducing the amount of free carbon, carbon monoxide and hydrocarbon to be discharged through engine exhaust, but also improving the engine performance.